This patch provides --fileflags, which preserves the st_flags stat() field.
Modified from a patch that was written by Rolf Grossmann.

To use this patch, run these commands for a successful build:

    patch -p1 <patches/fileflags.diff
    ./prepare-source
    ./configure
    make

based-on: 1ddcdaf3f6808ba53aef9e19f630a18808de22ac
diff --git a/Makefile.in b/Makefile.in
--- a/Makefile.in
+++ b/Makefile.in
@@ -42,7 +42,7 @@ popt_OBJS=popt/findme.o  popt/popt.o  popt/poptconfig.o \
 	popt/popthelp.o popt/poptparse.o
 OBJS=$(OBJS1) $(OBJS2) $(OBJS3) $(DAEMON_OBJ) $(LIBOBJ) $(ZLIBOBJ) @BUILD_POPT@
 
-TLS_OBJ = tls.o syscall.o lib/compat.o lib/snprintf.o lib/permstring.o lib/sysxattrs.o @BUILD_POPT@
+TLS_OBJ = tls.o syscall.o t_stub.o lib/compat.o lib/snprintf.o lib/permstring.o lib/sysxattrs.o @BUILD_POPT@
 
 # Programs we must have to run the test cases
 CHECK_PROGS = rsync$(EXEEXT) tls$(EXEEXT) getgroups$(EXEEXT) getfsdev$(EXEEXT) \
@@ -107,7 +107,7 @@ getgroups$(EXEEXT): getgroups.o
 getfsdev$(EXEEXT): getfsdev.o
 	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ getfsdev.o $(LIBS)
 
-TRIMSLASH_OBJ = trimslash.o syscall.o lib/compat.o lib/snprintf.o
+TRIMSLASH_OBJ = trimslash.o syscall.o t_stub.o lib/compat.o lib/snprintf.o
 trimslash$(EXEEXT): $(TRIMSLASH_OBJ)
 	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $(TRIMSLASH_OBJ) $(LIBS)
 
diff --git a/compat.c b/compat.c
--- a/compat.c
+++ b/compat.c
@@ -43,9 +43,11 @@ extern int checksum_seed;
 extern int basis_dir_cnt;
 extern int prune_empty_dirs;
 extern int protocol_version;
+extern int force_change;
 extern int protect_args;
 extern int preserve_uid;
 extern int preserve_gid;
+extern int preserve_fileflags;
 extern int preserve_acls;
 extern int preserve_xattrs;
 extern int need_messages_from_generator;
@@ -63,7 +65,7 @@ extern char *iconv_opt;
 #endif
 
 /* These index values are for the file-list's extra-attribute array. */
-int uid_ndx, gid_ndx, acls_ndx, xattrs_ndx, unsort_ndx;
+int uid_ndx, gid_ndx, fileflags_ndx, acls_ndx, xattrs_ndx, unsort_ndx;
 
 int receiver_symlink_times = 0; /* receiver can set the time on a symlink */
 int sender_symlink_iconv = 0;	/* sender should convert symlink content */
@@ -140,6 +142,8 @@ void setup_protocol(int f_out,int f_in)
 		uid_ndx = ++file_extra_cnt;
 	if (preserve_gid)
 		gid_ndx = ++file_extra_cnt;
+	if (preserve_fileflags || (force_change && !am_sender))
+		fileflags_ndx = ++file_extra_cnt;
 	if (preserve_acls && !am_sender)
 		acls_ndx = ++file_extra_cnt;
 	if (preserve_xattrs)
diff --git a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
@@ -569,6 +569,7 @@ AC_FUNC_UTIME_NULL
 AC_FUNC_ALLOCA
 AC_CHECK_FUNCS(waitpid wait4 getcwd strdup chown chmod lchmod mknod mkfifo \
     fchmod fstat ftruncate strchr readlink link utime utimes lutimes strftime \
+    chflags \
     memmove lchown vsnprintf snprintf vasprintf asprintf setsid strpbrk \
     strlcat strlcpy strtol mallinfo getgroups setgroups geteuid getegid \
     setlocale setmode open64 lseek64 mkstemp64 mtrace va_copy __va_copy \
diff --git a/flist.c b/flist.c
--- a/flist.c
+++ b/flist.c
@@ -51,6 +51,7 @@ extern int preserve_links;
 extern int preserve_hard_links;
 extern int preserve_devices;
 extern int preserve_specials;
+extern int preserve_fileflags;
 extern int delete_during;
 extern int eol_nulls;
 extern int relative_paths;
@@ -394,6 +395,9 @@ static void send_file_entry(int f, const char *fname, struct file_struct *file,
 {
 	static time_t modtime;
 	static mode_t mode;
+#ifdef SUPPORT_FILEFLAGS
+	static uint32 fileflags;
+#endif
 #ifdef SUPPORT_HARD_LINKS
 	static int64 dev;
 #endif
@@ -423,6 +427,14 @@ static void send_file_entry(int f, const char *fname, struct file_struct *file,
 		xflags |= XMIT_SAME_MODE;
 	else
 		mode = file->mode;
+#ifdef SUPPORT_FILEFLAGS
+	if (preserve_fileflags) {
+		if (F_FFLAGS(file) == fileflags)
+			xflags |= XMIT_SAME_FLAGS;
+		else
+			fileflags = F_FFLAGS(file);
+	}
+#endif
 
 	if (preserve_devices && IS_DEVICE(mode)) {
 		if (protocol_version < 28) {
@@ -547,6 +559,10 @@ static void send_file_entry(int f, const char *fname, struct file_struct *file,
 	}
 	if (!(xflags & XMIT_SAME_MODE))
 		write_int(f, to_wire_mode(mode));
+#ifdef SUPPORT_FILEFLAGS
+	if (preserve_fileflags && !(xflags & XMIT_SAME_FLAGS))
+		write_int(f, (int)fileflags);
+#endif
 	if (preserve_uid && !(xflags & XMIT_SAME_UID)) {
 		if (protocol_version < 30)
 			write_int(f, uid);
@@ -634,6 +650,9 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 {
 	static int64 modtime;
 	static mode_t mode;
+#ifdef SUPPORT_FILEFLAGS
+	static uint32 fileflags;
+#endif
 #ifdef SUPPORT_HARD_LINKS
 	static int64 dev;
 #endif
@@ -731,6 +750,10 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 			file_length = F_LENGTH(first);
 			modtime = first->modtime;
 			mode = first->mode;
+#ifdef SUPPORT_FILEFLAGS
+			if (preserve_fileflags)
+				fileflags = F_FFLAGS(first);
+#endif
 			if (preserve_uid)
 				uid = F_OWNER(first);
 			if (preserve_gid)
@@ -768,6 +791,10 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 
 	if (chmod_modes && !S_ISLNK(mode))
 		mode = tweak_mode(mode, chmod_modes);
+#ifdef SUPPORT_FILEFLAGS
+	if (preserve_fileflags && !(xflags & XMIT_SAME_FLAGS))
+		fileflags = (uint32)read_int(f);
+#endif
 
 	if (preserve_uid && !(xflags & XMIT_SAME_UID)) {
 		if (protocol_version < 30)
@@ -909,6 +936,10 @@ static struct file_struct *recv_file_entry(int f, struct file_list *flist, int x
 	}
 #endif
 	file->mode = mode;
+#ifdef SUPPORT_FILEFLAGS
+	if (fileflags_ndx) /* check the ndx for force_change w/o preserve_fileflags */
+		F_FFLAGS(file) = fileflags;
+#endif
 	if (preserve_uid)
 		F_OWNER(file) = uid;
 	if (preserve_gid) {
@@ -1283,6 +1314,10 @@ struct file_struct *make_file(const char *fname, struct file_list *flist,
 	}
 #endif
 	file->mode = st.st_mode;
+#if defined SUPPORT_FILEFLAGS || defined SUPPORT_FORCE_CHANGE
+	if (fileflags_ndx)
+		F_FFLAGS(file) = st.st_flags;
+#endif
 	if (preserve_uid)
 		F_OWNER(file) = st.st_uid;
 	if (preserve_gid)
@@ -1429,6 +1464,9 @@ static struct file_struct *send_file_name(int f, struct file_list *flist,
 #ifdef SUPPORT_XATTRS
 		if (preserve_xattrs) {
 			sx.st.st_mode = file->mode;
+#ifdef SUPPORT_FILEFLAGS
+			sx.st.st_flags = preserve_fileflags ? F_FFLAGS(file) : 0;
+#endif
 			sx.xattr = NULL;
 			if (get_xattr(fname, &sx) < 0) {
 				io_error |= IOERR_GENERAL;
diff --git a/generator.c b/generator.c
--- a/generator.c
+++ b/generator.c
@@ -35,6 +35,7 @@ extern int do_progress;
 extern int relative_paths;
 extern int implied_dirs;
 extern int keep_dirlinks;
+extern int force_change;
 extern int preserve_acls;
 extern int preserve_xattrs;
 extern int preserve_links;
@@ -42,6 +43,7 @@ extern int preserve_devices;
 extern int preserve_specials;
 extern int preserve_hard_links;
 extern int preserve_executability;
+extern int preserve_fileflags;
 extern int preserve_perms;
 extern int preserve_times;
 extern int delete_mode;
@@ -164,11 +166,15 @@ static enum delret delete_item(char *fbuf, uint16 mode, uint16 flags)
 	}
 
 	if (flags & DEL_NO_UID_WRITE)
-		do_chmod(fbuf, mode | S_IWUSR);
+		do_chmod(fbuf, mode | S_IWUSR, NO_FFLAGS);
 
 	if (S_ISDIR(mode) && !(flags & DEL_DIR_IS_EMPTY)) {
 		/* This only happens on the first call to delete_item() since
 		 * delete_dir_contents() always calls us w/DEL_DIR_IS_EMPTY. */
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change)
+			make_mutable(fbuf, NULL, NO_FFLAGS, force_change);
+#endif
 		ignore_perishable = 1;
 		/* If DEL_RECURSE is not set, this just reports emptiness. */
 		ret = delete_dir_contents(fbuf, flags);
@@ -285,8 +291,14 @@ static enum delret delete_dir_contents(char *fname, uint16 flags)
 		}
 
 		strlcpy(p, fp->basename, remainder);
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change) {
+			mode_t mode = fp->mode;
+			make_mutable(fname, &mode, F_FFLAGS(fp), force_change);
+		}
+#endif
 		if (!(fp->mode & S_IWUSR) && !am_root && fp->flags & FLAG_OWNED_BY_US)
-			do_chmod(fname, fp->mode | S_IWUSR);
+			do_chmod(fname, fp->mode | S_IWUSR, NO_FFLAGS);
 		/* Save stack by recursing to ourself directly. */
 		if (S_ISDIR(fp->mode)) {
 			if (delete_dir_contents(fname, flags | DEL_RECURSE) != DR_SUCCESS)
@@ -647,6 +659,10 @@ int unchanged_attrs(const char *fname, struct file_struct *file, stat_x *sxp)
 			return 0;
 		if (perms_differ(file, sxp))
 			return 0;
+#ifdef SUPPORT_FILEFLAGS
+		if (preserve_fileflags && sxp->st.st_flags != F_FFLAGS(file))
+			return 0;
+#endif
 		if (ownership_differs(file, sxp))
 			return 0;
 #ifdef SUPPORT_ACLS
@@ -698,6 +714,11 @@ void itemize(const char *fnamecmp, struct file_struct *file, int ndx, int statre
 		if (gid_ndx && !(file->flags & FLAG_SKIP_GROUP)
 		    && sxp->st.st_gid != (gid_t)F_GROUP(file))
 			iflags |= ITEM_REPORT_GROUP;
+#ifdef SUPPORT_FILEFLAGS
+		if (preserve_fileflags && !S_ISLNK(file->mode)
+		 && sxp->st.st_flags != F_FFLAGS(file))
+			iflags |= ITEM_REPORT_FFLAGS;
+#endif
 #ifdef SUPPORT_ACLS
 		if (preserve_acls && !S_ISLNK(file->mode)) {
 			if (!ACL_READY(*sxp))
@@ -1491,6 +1512,10 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 			file->mode = dest_mode(file->mode, sx.st.st_mode,
 					       dflt_perms, statret == 0);
 		}
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change && !preserve_fileflags)
+			F_FFLAGS(file) = sx.st.st_flags;
+#endif
 		if (statret != 0 && basis_dir[0] != NULL) {
 			int j = try_dests_non(file, fname, ndx, fnamecmpbuf, &sx,
 					      itemizing, code);
@@ -1526,10 +1551,17 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 		/* We need to ensure that the dirs in the transfer have writable
 		 * permissions during the time we are putting files within them.
 		 * This is then fixed after the transfer is done. */
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change && F_FFLAGS(file) & force_change) {
+			mode_t mode = file->mode;
+			if (make_mutable(fname, &mode, F_FFLAGS(file), force_change))
+				need_retouch_dir_perms = 1;
+		}
+#endif
 #ifdef HAVE_CHMOD
 		if (!am_root && !(file->mode & S_IWUSR) && dir_tweaking) {
 			mode_t mode = file->mode | S_IWUSR;
-			if (do_chmod(fname, mode) < 0) {
+			if (do_chmod(fname, mode, 0) < 0) {
 				rsyserr(FERROR_XFER, errno,
 					"failed to modify permissions on %s",
 					full_fname(fname));
@@ -1572,6 +1604,10 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 		file->mode = dest_mode(file->mode, sx.st.st_mode, dflt_perms,
 				       exists);
 	}
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && !preserve_fileflags)
+		F_FFLAGS(file) = sx.st.st_flags;
+#endif
 
 #ifdef SUPPORT_HARD_LINKS
 	if (preserve_hard_links && F_HLINK_NOT_FIRST(file)
@@ -2115,13 +2151,17 @@ static void touch_up_dirs(struct file_list *flist, int ndx)
 			continue;
 		fname = f_name(file, NULL);
 		if (fix_dir_perms)
-			do_chmod(fname, file->mode);
+			do_chmod(fname, file->mode, 0);
 		if (need_retouch_dir_times) {
 			STRUCT_STAT st;
 			if (link_stat(fname, &st, 0) == 0
 			 && cmp_time(st.st_mtime, file->modtime) != 0)
-				set_modtime(fname, file->modtime, file->mode);
+				set_modtime(fname, file->modtime, file->mode, 0);
 		}
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change && F_FFLAGS(file) & force_change)
+			undo_make_mutable(fname, F_FFLAGS(file));
+#endif
 		if (counter >= loopchk_limit) {
 			if (allowed_lull)
 				maybe_send_keepalive();
diff --git a/log.c b/log.c
--- a/log.c
+++ b/log.c
@@ -658,7 +658,7 @@ static void log_formatted(enum logcode code, const char *format, const char *op,
 			c[5] = !(iflags & ITEM_REPORT_PERMS) ? '.' : 'p';
 			c[6] = !(iflags & ITEM_REPORT_OWNER) ? '.' : 'o';
 			c[7] = !(iflags & ITEM_REPORT_GROUP) ? '.' : 'g';
-			c[8] = !(iflags & ITEM_REPORT_ATIME) ? '.' : 'u';
+			c[8] = !(iflags & ITEM_REPORT_FFLAGS) ? '.' : 'f';
 			c[9] = !(iflags & ITEM_REPORT_ACL) ? '.' : 'a';
 			c[10] = !(iflags & ITEM_REPORT_XATTR) ? '.' : 'x';
 			c[11] = '\0';
diff --git a/main.c b/main.c
--- a/main.c
+++ b/main.c
@@ -26,6 +26,9 @@
 #if defined CONFIG_LOCALE && defined HAVE_LOCALE_H
 #include <locale.h>
 #endif
+#ifdef SUPPORT_FORCE_CHANGE
+#include <sys/sysctl.h>
+#endif
 
 extern int verbose;
 extern int dry_run;
@@ -51,6 +54,7 @@ extern int protocol_version;
 extern int file_total;
 extern int recurse;
 extern int xfer_dirs;
+extern int force_change;
 extern int protect_args;
 extern int relative_paths;
 extern int sanitize_paths;
@@ -753,6 +757,22 @@ static int do_recv(int f_in, int f_out, char *local_name)
 	 * points to an identical file won't be replaced by the referent. */
 	copy_links = copy_dirlinks = copy_unsafe_links = 0;
 
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change & SYS_IMMUTABLE) {
+		/* Determine whether we'll be able to unlock a system immutable item. */
+		int mib[2];
+		int securityLevel = 0;
+		size_t len = sizeof securityLevel;
+
+		mib[0] = CTL_KERN;
+		mib[1] = KERN_SECURELVL;
+		if (sysctl(mib, 2, &securityLevel, &len, NULL, 0) == 0 && securityLevel > 0) {
+			rprintf(FERROR, "System security level is too high to force mutability on system immutable files and directories.\n");
+			exit_cleanup(RERR_UNSUPPORTED);
+		}
+	}
+#endif
+
 #ifdef SUPPORT_HARD_LINKS
 	if (preserve_hard_links && !inc_recurse)
 		match_hard_links(first_flist);
diff --git a/options.c b/options.c
--- a/options.c
+++ b/options.c
@@ -53,6 +53,7 @@ int preserve_hard_links = 0;
 int preserve_acls = 0;
 int preserve_xattrs = 0;
 int preserve_perms = 0;
+int preserve_fileflags = 0;
 int preserve_executability = 0;
 int preserve_devices = 0;
 int preserve_specials = 0;
@@ -84,6 +85,7 @@ int implied_dirs = 1;
 int numeric_ids = 0;
 int allow_8bit_chars = 0;
 int force_delete = 0;
+int force_change = 0;
 int io_timeout = 0;
 int prune_empty_dirs = 0;
 int use_qsort = 0;
@@ -223,6 +225,7 @@ static void print_rsync_version(enum logcode f)
 	char const *links = "no ";
 	char const *iconv = "no ";
 	char const *ipv6 = "no ";
+	char const *fileflags = "no ";
 	STRUCT_STAT *dumstat;
 
 #if SUBPROTOCOL_VERSION != 0
@@ -256,6 +259,9 @@ static void print_rsync_version(enum logcode f)
 #ifdef CAN_SET_SYMLINK_TIMES
 	symtimes = "";
 #endif
+#ifdef SUPPORT_FILEFLAGS
+	fileflags = "";
+#endif
 
 	rprintf(f, "%s  version %s  protocol version %d%s\n",
 		RSYNC_NAME, RSYNC_VERSION, PROTOCOL_VERSION, subprotocol);
@@ -269,8 +275,8 @@ static void print_rsync_version(enum logcode f)
 		(int)(sizeof (int64) * 8));
 	rprintf(f, "    %ssocketpairs, %shardlinks, %ssymlinks, %sIPv6, batchfiles, %sinplace,\n",
 		got_socketpair, hardlinks, links, ipv6, have_inplace);
-	rprintf(f, "    %sappend, %sACLs, %sxattrs, %siconv, %ssymtimes\n",
-		have_inplace, acls, xattrs, iconv, symtimes);
+	rprintf(f, "    %sappend, %sACLs, %sxattrs, %siconv, %ssymtimes, %sfile-flags\n",
+		have_inplace, acls, xattrs, iconv, symtimes, fileflags);
 
 #ifdef MAINTAINER_MODE
 	rprintf(f, "Panic Action: \"%s\"\n", get_panic_action());
@@ -337,6 +343,9 @@ void usage(enum logcode F)
   rprintf(F," -K, --keep-dirlinks         treat symlinked dir on receiver as dir\n");
   rprintf(F," -H, --hard-links            preserve hard links\n");
   rprintf(F," -p, --perms                 preserve permissions\n");
+#ifdef SUPPORT_FILEFLAGS
+  rprintf(F,"     --fileflags             preserve file-flags (aka chflags)\n");
+#endif
   rprintf(F," -E, --executability         preserve the file's executability\n");
   rprintf(F,"     --chmod=CHMOD           affect file and/or directory permissions\n");
 #ifdef SUPPORT_ACLS
@@ -374,7 +383,12 @@ void usage(enum logcode F)
   rprintf(F,"     --delete-after          receiver deletes after transfer, not during\n");
   rprintf(F,"     --delete-excluded       also delete excluded files from destination dirs\n");
   rprintf(F,"     --ignore-errors         delete even if there are I/O errors\n");
-  rprintf(F,"     --force                 force deletion of directories even if not empty\n");
+  rprintf(F,"     --force-delete          force deletion of directories even if not empty\n");
+#ifdef SUPPORT_FORCE_CHANGE
+  rprintf(F,"     --force-change          affect user-/system-immutable files/dirs\n");
+  rprintf(F,"     --force-uchange         affect user-immutable files/dirs\n");
+  rprintf(F,"     --force-schange         affect system-immutable files/dirs\n");
+#endif
   rprintf(F,"     --max-delete=NUM        don't delete more than NUM files\n");
   rprintf(F,"     --max-size=SIZE         don't transfer any file larger than SIZE\n");
   rprintf(F,"     --min-size=SIZE         don't transfer any file smaller than SIZE\n");
@@ -479,6 +493,10 @@ static struct poptOption long_options[] = {
   {"perms",           'p', POPT_ARG_VAL,    &preserve_perms, 1, 0, 0 },
   {"no-perms",         0,  POPT_ARG_VAL,    &preserve_perms, 0, 0, 0 },
   {"no-p",             0,  POPT_ARG_VAL,    &preserve_perms, 0, 0, 0 },
+#ifdef SUPPORT_FILEFLAGS
+  {"fileflags",        0,  POPT_ARG_VAL,    &preserve_fileflags, 1, 0, 0 },
+  {"no-fileflags",     0,  POPT_ARG_VAL,    &preserve_fileflags, 0, 0, 0 },
+#endif
   {"executability",   'E', POPT_ARG_NONE,   &preserve_executability, 0, 0, 0 },
   {"acls",            'A', POPT_ARG_NONE,   0, 'A', 0, 0 },
   {"no-acls",          0,  POPT_ARG_VAL,    &preserve_acls, 0, 0, 0 },
@@ -557,6 +575,14 @@ static struct poptOption long_options[] = {
   {"remove-source-files",0,POPT_ARG_VAL,    &remove_source_files, 1, 0, 0 },
   {"force",            0,  POPT_ARG_VAL,    &force_delete, 1, 0, 0 },
   {"no-force",         0,  POPT_ARG_VAL,    &force_delete, 0, 0, 0 },
+  {"force-delete",     0,  POPT_ARG_VAL,    &force_delete, 1, 0, 0 },
+  {"no-force-delete",  0,  POPT_ARG_VAL,    &force_delete, 0, 0, 0 },
+#ifdef SUPPORT_FORCE_CHANGE
+  {"force-change",     0,  POPT_ARG_VAL,    &force_change, ALL_IMMUTABLE, 0, 0 },
+  {"no-force-change",  0,  POPT_ARG_VAL,    &force_change, 0, 0, 0 },
+  {"force-uchange",    0,  POPT_ARG_VAL,    &force_change, USR_IMMUTABLE, 0, 0 },
+  {"force-schange",    0,  POPT_ARG_VAL,    &force_change, SYS_IMMUTABLE, 0, 0 },
+#endif
   {"ignore-errors",    0,  POPT_ARG_VAL,    &ignore_errors, 1, 0, 0 },
   {"no-ignore-errors", 0,  POPT_ARG_VAL,    &ignore_errors, 0, 0, 0 },
   {"max-delete",       0,  POPT_ARG_INT,    &max_delete, 0, 0, 0 },
@@ -1879,6 +1905,9 @@ void server_options(char **args, int *argc_p)
 	if (xfer_dirs && !recurse && delete_mode && am_sender)
 		args[ac++] = "--no-r";
 
+	if (preserve_fileflags)
+		args[ac++] = "--fileflags";
+
 	if (do_compression && def_compress_level != Z_DEFAULT_COMPRESSION) {
 		if (asprintf(&arg, "--compress-level=%d", def_compress_level) < 0)
 			goto oom;
@@ -1966,6 +1995,16 @@ void server_options(char **args, int *argc_p)
 			args[ac++] = "--delete-excluded";
 		if (force_delete)
 			args[ac++] = "--force";
+#ifdef SUPPORT_FORCE_CHANGE
+		if (force_change) {
+			if (force_change == ALL_IMMUTABLE)
+				args[ac++] = "--force-change";
+			else if (force_change == USR_IMMUTABLE)
+				args[ac++] = "--force-uchange";
+			else if (force_change == SYS_IMMUTABLE)
+				args[ac++] = "--force-schange";
+		}
+#endif
 		if (write_batch < 0)
 			args[ac++] = "--only-write-batch=X";
 		if (am_root > 1)
diff --git a/rsync.c b/rsync.c
--- a/rsync.c
+++ b/rsync.c
@@ -29,9 +29,11 @@
 
 extern int verbose;
 extern int dry_run;
+extern int force_change;
 extern int preserve_acls;
 extern int preserve_xattrs;
 extern int preserve_perms;
+extern int preserve_fileflags;
 extern int preserve_executability;
 extern int preserve_times;
 extern int am_root;
@@ -374,6 +376,74 @@ mode_t dest_mode(mode_t flist_mode, mode_t stat_mode, int dflt_perms,
 	return new_mode;
 }
 
+#if defined SUPPORT_FILEFLAGS || defined SUPPORT_FORCE_CHANGE
+/* Set a file's st_flags. */
+static int set_fileflags(const char *fname, uint32 fileflags)
+{
+	if (do_chflags(fname, fileflags) != 0) {
+		rsyserr(FERROR_XFER, errno,
+			"failed to set fileflags (%x) on %s",
+			fileflags, full_fname(fname));
+		return 0;
+	}
+
+	return 1;
+}
+
+/* Remove immutable flags from an object, so it can be altered/removed.
+ * Returns the fileflags if flags were removed, otherwise 0.  If the
+ * fileflags value is NO_FFLAGS, we will stat the fname to figure out
+ * what the flags are, and return the mode via *mode_ptr (if non-NULL). */
+uint32 make_mutable(const char *fname, mode_t *mode_ptr, uint32 fileflags, uint32 iflags)
+{
+	if (fileflags == NO_FFLAGS) {
+		STRUCT_STAT st;
+		if (x_lstat(fname, &st, NULL) < 0)
+			return 0;
+		fileflags = st.st_flags;
+		if (mode_ptr)
+			*mode_ptr = st.st_mode;
+		else
+			mode_ptr = &st.st_mode;
+	}
+
+	if ((mode_ptr && S_ISLNK(*mode_ptr)) || !(fileflags & iflags))
+		return 0;
+
+	if (!set_fileflags(fname, fileflags & ~iflags))
+		return 0;
+
+	return fileflags;
+}
+
+/* Undo a prior make_mutable() call that returned a 1. */
+int undo_make_mutable(const char *fname, uint32 fileflags)
+{
+	if (!set_fileflags(fname, fileflags)) {
+		rsyserr(FINFO, errno, "failed to relock %s", full_fname(fname));
+		return -1;
+	}
+	return 1;
+}
+
+/* This returns the st_flags value if the parent directory was made mutable, otherwise 0.
+ * It stores the parent directory path into parent_dirbuf. */
+int make_parentdir_mutable(const char *fname, uint32 iflags, char *parent_dirbuf, int parent_dirbuf_size)
+{
+	char *slash = strrchr(fname, '/');
+
+	if (slash) {
+		int len = slash - fname;
+		if (len >= parent_dirbuf_size)
+			return 0;
+		strlcpy(parent_dirbuf, fname, len+1);
+	} else
+		strlcpy(parent_dirbuf, ".", parent_dirbuf_size);
+
+	return make_mutable(parent_dirbuf, NULL, NO_FFLAGS, iflags);
+}
+#endif
+
 int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 		   const char *fnamecmp, int flags)
 {
@@ -382,6 +452,9 @@ int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 	int change_uid, change_gid;
 	mode_t new_mode = file->mode;
 	int inherit;
+#ifdef SUPPORT_FORCE_CHANGE
+	int became_mutable = 0;
+#endif
 
 	if (!sxp) {
 		if (dry_run)
@@ -411,6 +484,11 @@ int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 	if (daemon_chmod_modes && !S_ISLNK(new_mode))
 		new_mode = tweak_mode(new_mode, daemon_chmod_modes);
 
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change)
+		became_mutable = make_mutable(fname, &sxp->st.st_mode, sxp->st.st_flags, force_change);
+#endif
+
 #ifdef SUPPORT_ACLS
 	if (preserve_acls && !S_ISLNK(file->mode) && !ACL_READY(*sxp))
 		get_acl(fname, sxp);
@@ -429,7 +507,7 @@ int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 		flags |= ATTRS_SKIP_MTIME;
 	if (!(flags & ATTRS_SKIP_MTIME)
 	    && cmp_time(sxp->st.st_mtime, file->modtime) != 0) {
-		int ret = set_modtime(fname, file->modtime, sxp->st.st_mode);
+		int ret = set_modtime(fname, file->modtime, sxp->st.st_mode, ST_FLAGS(sxp->st));
 		if (ret < 0) {
 			rsyserr(FERROR_XFER, errno, "failed to set times on %s",
 				full_fname(fname));
@@ -465,7 +543,7 @@ int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 		if (am_root >= 0) {
 			uid_t uid = change_uid ? (uid_t)F_OWNER(file) : sxp->st.st_uid;
 			gid_t gid = change_gid ? (gid_t)F_GROUP(file) : sxp->st.st_gid;
-			if (do_lchown(fname, uid, gid) != 0) {
+			if (do_lchown(fname, uid, gid, sxp->st.st_mode, ST_FLAGS(sxp->st)) != 0) {
 				/* We shouldn't have attempted to change uid
 				 * or gid unless have the privilege. */
 				rsyserr(FERROR_XFER, errno, "%s %s failed",
@@ -503,7 +581,7 @@ int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 
 #ifdef HAVE_CHMOD
 	if (!BITS_EQUAL(sxp->st.st_mode, new_mode, CHMOD_BITS)) {
-		int ret = am_root < 0 ? 0 : do_chmod(fname, new_mode);
+		int ret = am_root < 0 ? 0 : do_chmod(fname, new_mode, ST_FLAGS(sxp->st));
 		if (ret < 0) {
 			rsyserr(FERROR_XFER, errno,
 				"failed to set permissions on %s",
@@ -515,6 +593,24 @@ int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 	}
 #endif
 
+#ifdef SUPPORT_FORCE_CHANGE
+	if (became_mutable)
+		undo_make_mutable(fname, sxp->st.st_flags);
+#endif
+
+#ifdef SUPPORT_FILEFLAGS
+	if (preserve_fileflags && !S_ISLNK(sxp->st.st_mode)
+	 && sxp->st.st_flags != F_FFLAGS(file)) {
+		uint32 fileflags = F_FFLAGS(file);
+		if (flags & ATTRS_DELAY_IMMUTABLE)
+			fileflags &= ~ALL_IMMUTABLE;
+		if (sxp->st.st_flags != fileflags
+		 && !set_fileflags(fname, fileflags))
+			goto cleanup;
+		updated = 1;
+	}
+#endif
+
 	if (verbose > 1 && flags & ATTRS_REPORT) {
 		if (updated)
 			rprintf(FCLIENT, "%s\n", fname);
@@ -578,7 +674,8 @@ int finish_transfer(const char *fname, const char *fnametmp,
 
 	/* Change permissions before putting the file into place. */
 	set_file_attrs(fnametmp, file, NULL, fnamecmp,
-		       ok_to_set_time ? 0 : ATTRS_SKIP_MTIME);
+		       ATTRS_DELAY_IMMUTABLE
+		       | (ok_to_set_time ? 0 : ATTRS_SKIP_MTIME));
 
 	/* move tmp file over real file */
 	if (verbose > 2)
@@ -597,6 +694,10 @@ int finish_transfer(const char *fname, const char *fnametmp,
 	}
 	if (ret == 0) {
 		/* The file was moved into place (not copied), so it's done. */
+#ifdef SUPPORT_FILEFLAGS
+		if (preserve_fileflags && F_FFLAGS(file) & ALL_IMMUTABLE)
+			set_fileflags(fname, F_FFLAGS(file));
+#endif
 		return 1;
 	}
 	/* The file was copied, so tweak the perms of the copied file.  If it
diff --git a/rsync.h b/rsync.h
--- a/rsync.h
+++ b/rsync.h
@@ -61,6 +61,7 @@
 #define XMIT_GROUP_NAME_FOLLOWS (1<<11) /* protocols 30 - now */
 #define XMIT_HLINK_FIRST (1<<12)	/* protocols 30 - now (HLINKED files only) */
 #define XMIT_IO_ERROR_ENDLIST (1<<12)	/* protocols 31*- now (w/XMIT_EXTENDED_FLAGS) (also protocol 30 w/'f' compat flag) */
+#define XMIT_SAME_FLAGS (1<<14)		/* protocols ?? - now */
 
 /* These flags are used in the live flist data. */
 
@@ -160,6 +161,7 @@
 
 #define ATTRS_REPORT		(1<<0)
 #define ATTRS_SKIP_MTIME	(1<<1)
+#define ATTRS_DELAY_IMMUTABLE	(1<<2)
 
 #define FULL_FLUSH	1
 #define NORMAL_FLUSH	0
@@ -186,6 +188,7 @@
 #define ITEM_REPORT_GROUP (1<<6)
 #define ITEM_REPORT_ACL (1<<7)
 #define ITEM_REPORT_XATTR (1<<8)
+#define ITEM_REPORT_FFLAGS (1<<9)
 #define ITEM_BASIS_TYPE_FOLLOWS (1<<11)
 #define ITEM_XNAME_FOLLOWS (1<<12)
 #define ITEM_IS_NEW (1<<13)
@@ -482,6 +485,28 @@ typedef unsigned int size_t;
 #endif
 #endif
 
+#define NO_FFLAGS ((uint32)-1)
+
+#ifdef HAVE_CHFLAGS
+#define SUPPORT_FILEFLAGS 1
+#define SUPPORT_FORCE_CHANGE 1
+#endif
+
+#if defined SUPPORT_FILEFLAGS || defined SUPPORT_FORCE_CHANGE
+#ifndef UF_NOUNLINK
+#define UF_NOUNLINK 0
+#endif
+#ifndef SF_NOUNLINK
+#define SF_NOUNLINK 0
+#endif
+#define USR_IMMUTABLE (UF_IMMUTABLE|UF_NOUNLINK|UF_APPEND)
+#define SYS_IMMUTABLE (SF_IMMUTABLE|SF_NOUNLINK|SF_APPEND)
+#define ALL_IMMUTABLE (USR_IMMUTABLE|SYS_IMMUTABLE)
+#define ST_FLAGS(st) (st.st_flags)
+#else
+#define ST_FLAGS(st) NO_FFLAGS
+#endif
+
 /* Find a variable that is either exactly 32-bits or longer.
  * If some code depends on 32-bit truncation, it will need to
  * take special action in a "#if SIZEOF_INT32 > 4" section. */
@@ -652,6 +677,7 @@ extern int file_extra_cnt;
 extern int inc_recurse;
 extern int uid_ndx;
 extern int gid_ndx;
+extern int fileflags_ndx;
 extern int acls_ndx;
 extern int xattrs_ndx;
 
@@ -689,6 +715,11 @@ extern int xattrs_ndx;
 /* When the associated option is on, all entries will have these present: */
 #define F_OWNER(f) REQ_EXTRA(f, uid_ndx)->unum
 #define F_GROUP(f) REQ_EXTRA(f, gid_ndx)->unum
+#if defined SUPPORT_FILEFLAGS || defined SUPPORT_FORCE_CHANGE
+#define F_FFLAGS(f) REQ_EXTRA(f, fileflags_ndx)->unum
+#else
+#define F_FFLAGS(f) NO_FFLAGS
+#endif
 #define F_ACL(f) REQ_EXTRA(f, acls_ndx)->num
 #define F_XATTR(f) REQ_EXTRA(f, xattrs_ndx)->num
 #define F_NDX(f) REQ_EXTRA(f, unsort_ndx)->num
diff --git a/rsync.yo b/rsync.yo
--- a/rsync.yo
+++ b/rsync.yo
@@ -342,6 +342,7 @@ to the detailed description below for a complete description.  verb(
  -K, --keep-dirlinks         treat symlinked dir on receiver as dir
  -H, --hard-links            preserve hard links
  -p, --perms                 preserve permissions
+     --fileflags             preserve file-flags (aka chflags)
  -E, --executability         preserve executability
      --chmod=CHMOD           affect file and/or directory permissions
  -A, --acls                  preserve ACLs (implies -p)
@@ -373,7 +374,10 @@ to the detailed description below for a complete description.  verb(
      --delete-after          receiver deletes after transfer, not before
      --delete-excluded       also delete excluded files from dest dirs
      --ignore-errors         delete even if there are I/O errors
-     --force                 force deletion of dirs even if not empty
+     --force-delete          force deletion of dirs even if not empty
+     --force-change          affect user/system immutable files/dirs
+     --force-uchange         affect user-immutable files/dirs
+     --force-schange         affect system-immutable files/dirs
      --max-delete=NUM        don't delete more than NUM files
      --max-size=SIZE         don't transfer any file larger than SIZE
      --min-size=SIZE         don't transfer any file smaller than SIZE
@@ -547,7 +551,8 @@ specified, in which case bf(-r) is not implied.
 
 Note that bf(-a) bf(does not preserve hardlinks), because
 finding multiply-linked files is expensive.  You must separately
-specify bf(-H).
+specify bf(-H).  Note also that for backward compatibility, bf(-a)
+currently does bf(not) imply the bf(--fileflags) option.
 
 dit(--no-OPTION) You may turn off one or more implied options by prefixing
 the option name with "no-".  Not all options may be prefixed with a "no-":
@@ -827,7 +832,7 @@ they would be using bf(--copy-links).
 Without this option, if the sending side has replaced a directory with a
 symlink to a directory, the receiving side will delete anything that is in
 the way of the new symlink, including a directory hierarchy (as long as
-bf(--force) or bf(--delete) is in effect).
+bf(--force-delete) or bf(--delete) is in effect).
 
 See also bf(--keep-dirlinks) for an analogous option for the receiving
 side.
@@ -990,6 +995,29 @@ Note that this option does not copy rsyncs special xattr values (e.g. those
 used by bf(--fake-super)) unless you repeat the option (e.g. -XX).  This
 "copy all xattrs" mode cannot be used with bf(--fake-super).
 
+dit(bf(--fileflags)) This option causes rsync to update the file-flags to be
+the same as the source files and directories (if your OS supports the
+bf(chflags)(2) system call).   Some flags can only be altered by the super-user
+and some might only be unset below a certain secure-level (usually single-user
+mode). It will not make files alterable that are set to immutable on the
+receiver.  To do that, see bf(--force-change), bf(--force-uchange), and
+bf(--force-schange).
+
+dit(bf(--force-change)) This option causes rsync to disable both user-immutable
+and system-immutable flags on files and directories that are being updated or
+deleted on the receiving side.  This option overrides bf(--force-uchange) and
+bf(--force-schange).
+
+dit(bf(--force-uchange)) This option causes rsync to disable user-immutable
+flags on files and directories that are being updated or deleted on the
+receiving side.  It does not try to affect system flags.  This option overrides
+bf(--force-change) and bf(--force-schange).
+
+dit(bf(--force-schange)) This option causes rsync to disable system-immutable
+flags on files and directories that are being updated or deleted on the
+receiving side.  It does not try to affect user flags.  This option overrides
+bf(--force-change) and bf(--force-schange).
+
 dit(bf(--chmod)) This option tells rsync to apply one or more
 comma-separated "chmod" strings to the permission of the files in the
 transfer.  The resulting value is treated as though it were the permissions
@@ -1260,12 +1288,13 @@ See bf(--delete) (which is implied) for more details on file-deletion.
 dit(bf(--ignore-errors)) Tells bf(--delete) to go ahead and delete files
 even when there are I/O errors.
 
-dit(bf(--force)) This option tells rsync to delete a non-empty directory
+dit(bf(--force-delete)) This option tells rsync to delete a non-empty directory
 when it is to be replaced by a non-directory.  This is only relevant if
 deletions are not active (see bf(--delete) for details).
 
-Note for older rsync versions: bf(--force) used to still be required when
-using bf(--delete-after), and it used to be non-functional unless the
+This option can be abbreviated bf(--force) for backward compatibility.
+Note that some older rsync versions used to still require bf(--force)
+when using bf(--delete-after), and it used to be non-functional unless the
 bf(--recursive) option was also enabled.
 
 dit(bf(--max-delete=NUM)) This tells rsync not to delete more than NUM
@@ -1753,7 +1782,7 @@ with older versions of rsync, but that also turns on the output of other
 verbose messages).
 
 The "%i" escape has a cryptic output that is 11 letters long.  The general
-format is like the string bf(YXcstpoguax), where bf(Y) is replaced by the
+format is like the string bf(YXcstpogfax), where bf(Y) is replaced by the
 type of update being done, bf(X) is replaced by the file-type, and the
 other letters represent attributes that may be output if they are being
 modified.
@@ -1809,7 +1838,7 @@ quote(itemization(
   sender's value (requires bf(--owner) and super-user privileges).
   it() A bf(g) means the group is different and is being updated to the
   sender's value (requires bf(--group) and the authority to set the group).
-  it() The bf(u) slot is reserved for future use.
+  it() The bf(f) means that the fileflags information changed.
   it() The bf(a) means that the ACL information changed.
   it() The bf(x) means that the extended attribute information changed.
 ))
diff --git a/syscall.c b/syscall.c
--- a/syscall.c
+++ b/syscall.c
@@ -33,6 +33,7 @@ extern int dry_run;
 extern int am_root;
 extern int read_only;
 extern int list_only;
+extern int force_change;
 extern int preserve_perms;
 extern int preserve_executability;
 
@@ -50,14 +51,56 @@ int do_unlink(const char *fname)
 {
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
-	return unlink(fname);
+	if (unlink(fname) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && (errno == EPERM || errno == EACCES)) {
+		char parent[MAXPATHLEN];
+		int parent_flags;
+		int saved_errno = errno;
+		int file_flags = make_mutable(fname, NULL, NO_FFLAGS, force_change);
+		if (file_flags && unlink(fname) == 0)
+			return 0;
+		parent_flags = make_parentdir_mutable(fname, force_change, parent, sizeof parent);
+		if (parent_flags) {
+			int ret = unlink(fname);
+			undo_make_mutable(parent, parent_flags);
+			if (ret == 0)
+				return 0;
+		}
+		if (file_flags)
+			undo_make_mutable(fname, file_flags);
+		errno = saved_errno;
+	}
+#endif
+
+	return -1;
 }
 
 int do_symlink(const char *fname1, const char *fname2)
 {
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
-	return symlink(fname1, fname2);
+	if (symlink(fname1, fname2) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && (errno == EPERM || errno == EACCES)) {
+		char parent[MAXPATHLEN];
+		int saved_errno = errno;
+		int parent_flags = make_parentdir_mutable(fname2, force_change, parent, sizeof parent);
+		if (parent_flags) {
+			int ret = symlink(fname1, fname2);
+			undo_make_mutable(parent, parent_flags);
+			if (ret == 0)
+				return 0;
+		}
+		errno = saved_errno;
+	}
+#endif
+
+	return -1;
 }
 
 #ifdef HAVE_LINK
@@ -65,18 +108,55 @@ int do_link(const char *fname1, const char *fname2)
 {
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
-	return link(fname1, fname2);
+	if (link(fname1, fname2) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && (errno == EPERM || errno == EACCES)) {
+		char parent[MAXPATHLEN];
+		int saved_errno = errno;
+		int parent_flags = make_parentdir_mutable(fname2, force_change, parent, sizeof parent);
+		if (parent_flags) {
+			int ret = link(fname1, fname2);
+			undo_make_mutable(parent, parent_flags);
+			if (ret == 0)
+				return 0;
+		}
+		errno = saved_errno;
+	}
+#endif
+
+	return -1;
 }
 #endif
 
-int do_lchown(const char *path, uid_t owner, gid_t group)
+int do_lchown(const char *path, uid_t owner, gid_t group, mode_t mode, uint32 fileflags)
 {
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
 #ifndef HAVE_LCHOWN
 #define lchown chown
 #endif
-	return lchown(path, owner, group);
+	if (lchown(path, owner, group) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && (errno == EPERM || errno == EACCES)) {
+		int saved_errno = errno;
+		fileflags = make_mutable(path, &mode, fileflags, force_change);
+		if (fileflags) {
+			int ret = lchown(path, owner, group);
+			undo_make_mutable(path, fileflags);
+			if (ret == 0)
+				return 0;
+		}
+		errno = saved_errno;
+	}
+#else
+	mode = fileflags = 0; /* avoid compiler warning */
+#endif
+
+	return -1;
 }
 
 int do_mknod(const char *pathname, mode_t mode, dev_t dev)
@@ -116,7 +196,7 @@ int do_mknod(const char *pathname, mode_t mode, dev_t dev)
 			return -1;
 		close(sock);
 #ifdef HAVE_CHMOD
-		return do_chmod(pathname, mode);
+		return do_chmod(pathname, mode, 0);
 #else
 		return 0;
 #endif
@@ -133,21 +213,63 @@ int do_rmdir(const char *pathname)
 {
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
-	return rmdir(pathname);
+	if (rmdir(pathname) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && (errno == EPERM || errno == EACCES)) {
+		char parent[MAXPATHLEN];
+		int parent_flags;
+		int saved_errno = errno;
+		int file_flags = make_mutable(pathname, NULL, NO_FFLAGS, force_change);
+		if (file_flags && rmdir(pathname) == 0)
+			return 0;
+		parent_flags = make_parentdir_mutable(pathname, force_change, parent, sizeof parent);
+		if (parent_flags) {
+			int ret = rmdir(pathname);
+			undo_make_mutable(parent, parent_flags);
+			if (ret == 0)
+				return 0;
+		}
+		if (file_flags)
+			undo_make_mutable(pathname, file_flags);
+		errno = saved_errno;
+	}
+#endif
+
+	return -1;
 }
 
 int do_open(const char *pathname, int flags, mode_t mode)
 {
+	int fd;
 	if (flags != O_RDONLY) {
 		RETURN_ERROR_IF(dry_run, 0);
 		RETURN_ERROR_IF_RO_OR_LO;
 	}
+	if ((fd = open(pathname, flags | O_BINARY, mode)) >= 0)
+		return fd;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && (errno == EPERM || errno == EACCES)) {
+		char parent[MAXPATHLEN];
+		int saved_errno = errno;
+		int parent_flags = make_parentdir_mutable(pathname, force_change, parent, sizeof parent);
+		if (parent_flags) {
+			fd = open(pathname, flags | O_BINARY, mode);
+			undo_make_mutable(parent, parent_flags);
+			if (fd >= 0)
+				return fd;
+		}
+		errno = saved_errno;
+	}
+#endif
 
-	return open(pathname, flags | O_BINARY, mode);
+	return -1;
 }
 
 #ifdef HAVE_CHMOD
-int do_chmod(const char *path, mode_t mode)
+int do_chmod(const char *path, mode_t mode, uint32 fileflags)
 {
 	int code;
 	if (dry_run) return 0;
@@ -170,17 +292,93 @@ int do_chmod(const char *path, mode_t mode)
 	} else
 		code = chmod(path, mode & CHMOD_BITS); /* DISCOURAGED FUNCTION */
 #endif /* !HAVE_LCHMOD */
+#ifdef SUPPORT_FORCE_CHANGE
+	if (code < 0 && force_change && (errno == EPERM || errno == EACCES) && !S_ISLNK(mode)) {
+		int saved_errno = errno;
+		fileflags = make_mutable(path, &mode, fileflags, force_change);
+		if (fileflags) {
+#ifdef HAVE_LCHMOD
+			code = lchmod(path, mode & CHMOD_BITS);
+#else
+			code = chmod(path, mode & CHMOD_BITS);
+#endif
+			undo_make_mutable(path, fileflags);
+			if (code == 0)
+				return 0;
+		}
+		errno = saved_errno;
+	}
+#else
+	fileflags = 0; /* avoid compiler warning */
+#endif
 	if (code != 0 && (preserve_perms || preserve_executability))
 		return code;
 	return 0;
 }
 #endif
 
+#ifdef HAVE_CHFLAGS
+int do_chflags(const char *path, uint32 fileflags)
+{
+	if (dry_run) return 0;
+	RETURN_ERROR_IF_RO_OR_LO;
+	return chflags(path, fileflags);
+}
+#endif
+
 int do_rename(const char *fname1, const char *fname2)
 {
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
-	return rename(fname1, fname2);
+	if (rename(fname1, fname2) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && (errno == EPERM || errno == EACCES)) {
+		int saved_errno = errno;
+		int ret = -1, file2_flags = 0;
+		int file1_flags = make_mutable(fname1, NULL, NO_FFLAGS, force_change);
+		if (file1_flags && rename(fname1, fname2) == 0)
+			ret = 0;
+		else {
+			file2_flags = make_mutable(fname2, NULL, NO_FFLAGS, force_change);
+			if (file2_flags && rename(fname1, fname2) == 0)
+				ret = 0;
+			else {
+				char parent1[MAXPATHLEN];
+				int parent1_flags = make_parentdir_mutable(fname1, force_change,
+							parent1, sizeof parent1);
+				if (parent1_flags && rename(fname1, fname2) == 0)
+					ret = 0;
+				else {
+					char parent2[MAXPATHLEN];
+					int parent2_flags = make_parentdir_mutable(fname2, force_change,
+								parent2, sizeof parent2);
+					if (parent2_flags) {
+						if (rename(fname1, fname2) == 0)
+							ret = 0;
+						undo_make_mutable(parent2, parent2_flags);
+					}
+				}
+				if (parent1_flags)
+					undo_make_mutable(parent1, parent1_flags);
+			}
+		}
+
+		if (ret == 0)
+			file2_flags = file1_flags; /* file1 is now file2 */
+		else if (file1_flags)
+			undo_make_mutable(fname1, file1_flags);
+		if (file2_flags)
+			undo_make_mutable(fname2, file2_flags);
+		if (ret == 0)
+			return 0;
+
+		errno = saved_errno;
+	}
+#endif
+
+	return -1;
 }
 
 #ifdef HAVE_FTRUNCATE
@@ -222,7 +420,25 @@ int do_mkdir(char *fname, mode_t mode)
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
 	trim_trailing_slashes(fname);
-	return mkdir(fname, mode);
+	if (mkdir(fname, mode) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	if (force_change && (errno == EPERM || errno == EACCES)) {
+		char parent[MAXPATHLEN];
+		int saved_errno = errno;
+		int parent_flags = make_parentdir_mutable(fname, force_change, parent, sizeof parent);
+		if (parent_flags) {
+			int ret = mkdir(fname, mode);
+			undo_make_mutable(parent, parent_flags);
+			if (ret == 0)
+				return 0;
+		}
+		errno = saved_errno;
+	}
+#endif
+
+	return -1;
 }
 
 /* like mkstemp but forces permissions */
@@ -235,7 +451,19 @@ int do_mkstemp(char *template, mode_t perms)
 #if defined HAVE_SECURE_MKSTEMP && defined HAVE_FCHMOD && (!defined HAVE_OPEN64 || defined HAVE_MKSTEMP64)
 	{
 		int fd = mkstemp(template);
-		if (fd == -1)
+#ifdef SUPPORT_FORCE_CHANGE
+		if (fd < 0 && force_change) {
+			char parent[MAXPATHLEN];
+			int saved_errno = errno;
+			int parent_flags = make_parentdir_mutable(template, force_change, parent, sizeof parent);
+			if (parent_flags) {
+				fd = mkstemp(template);
+				undo_make_mutable(parent, parent_flags);
+			}
+			errno = saved_errno;
+		}
+#endif
+		if (fd < 0)
 			return -1;
 		if (fchmod(fd, perms) != 0 && preserve_perms) {
 			int errno_save = errno;
@@ -302,7 +530,7 @@ OFF_T do_lseek(int fd, OFF_T offset, int whence)
 }
 
 #ifdef HAVE_UTIMENSAT
-int do_utimensat(const char *fname, time_t modtime, uint32 mod_nsec)
+int do_utimensat(const char *fname, time_t modtime, uint32 mod_nsec, mode_t mode, uint32 fileflags)
 {
 	struct timespec t[2];
 
@@ -313,12 +541,26 @@ int do_utimensat(const char *fname, time_t modtime, uint32 mod_nsec)
 	t[0].tv_nsec = UTIME_NOW;
 	t[1].tv_sec = modtime;
 	t[1].tv_nsec = mod_nsec;
-	return utimensat(AT_FDCWD, fname, t, AT_SYMLINK_NOFOLLOW);
+	if (utimensat(AT_FDCWD, fname, t, AT_SYMLINK_NOFOLLOW) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	fileflags = make_mutable(fname, &mode, fileflags, force_change);
+	if (fileflags) {
+		if (utimensat(AT_FDCWD, fname, t, AT_SYMLINK_NOFOLLOW) == 0)
+			return 0;
+		undo_make_mutable(fname, fileflags);
+	}
+#else
+	mode = fileflags; /* avoid compiler warning */
+#endif
+
+	return -1;
 }
 #endif
 
 #ifdef HAVE_LUTIMES
-int do_lutimes(const char *fname, time_t modtime, uint32 mod_nsec)
+int do_lutimes(const char *fname, time_t modtime, uint32 mod_nsec, mode_t mode, uint32 fileflags)
 {
 	struct timeval t[2];
 
@@ -329,12 +571,26 @@ int do_lutimes(const char *fname, time_t modtime, uint32 mod_nsec)
 	t[0].tv_usec = 0;
 	t[1].tv_sec = modtime;
 	t[1].tv_usec = mod_nsec / 1000;
-	return lutimes(fname, t);
+	if (lutimes(fname, t) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	fileflags = make_mutable(fname, &mode, fileflags, force_change);
+	if (fileflags) {
+		if (lutimes(fname, t) == 0)
+			return 0;
+		undo_make_mutable(fname, fileflags);
+	}
+#else
+	mode = fileflags; /* avoid compiler warning */
+#endif
+
+	return -1;
 }
 #endif
 
 #ifdef HAVE_UTIMES
-int do_utimes(const char *fname, time_t modtime, uint32 mod_nsec)
+int do_utimes(const char *fname, time_t modtime, uint32 mod_nsec, mode_t mode, uint32 fileflags)
 {
 	struct timeval t[2];
 
@@ -345,14 +601,28 @@ int do_utimes(const char *fname, time_t modtime, uint32 mod_nsec)
 	t[0].tv_usec = 0;
 	t[1].tv_sec = modtime;
 	t[1].tv_usec = mod_nsec / 1000;
-	return utimes(fname, t);
+	if (utimes(fname, t) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	fileflags = make_mutable(fname, &mode, fileflags, force_change);
+	if (fileflags) {
+		if (utimes(fname, t) == 0)
+			return 0;
+		undo_make_mutable(fname, fileflags);
+	}
+#else
+	mode = fileflags; /* avoid compiler warning */
+#endif
+
+	return -1;
 }
 
 #elif defined HAVE_UTIME
-int do_utime(const char *fname, time_t modtime, UNUSED(uint32 mod_nsec))
+int do_utime(const char *fname, time_t modtime, UNUSED(uint32 mod_nsec), mode_t mode, uint32 fileflags)
 {
 #ifdef HAVE_STRUCT_UTIMBUF
-	struct utimbuf tbuf;
+	struct utimbuf tbuf, *t = &tbuf;
 #else
 	time_t t[2];
 #endif
@@ -360,15 +630,28 @@ int do_utime(const char *fname, time_t modtime, UNUSED(uint32 mod_nsec))
 	if (dry_run) return 0;
 	RETURN_ERROR_IF_RO_OR_LO;
 
-# ifdef HAVE_STRUCT_UTIMBUF
+#ifdef HAVE_STRUCT_UTIMBUF
 	tbuf.actime = time(NULL);
 	tbuf.modtime = modtime;
-	return utime(fname, &tbuf);
-# else
+#else
 	t[0] = time(NULL);
 	t[1] = modtime;
-	return utime(fname, t);
-# endif
+#endif
+	if (utime(fname, t) == 0)
+		return 0;
+
+#ifdef SUPPORT_FORCE_CHANGE
+	fileflags = make_mutable(fname, &mode, fileflags, force_change);
+	if (fileflags) {
+		if (utime(fname, t) == 0)
+			return 0;
+		undo_make_mutable(fname, fileflags);
+	}
+#else
+	mode = fileflags; /* avoid compiler warning */
+#endif
+
+	return -1;
 }
 
 #else
diff --git a/t_stub.c b/t_stub.c
--- a/t_stub.c
+++ b/t_stub.c
@@ -26,6 +26,7 @@ int module_id = -1;
 int relative_paths = 0;
 int human_readable = 0;
 int module_dirlen = 0;
+int force_change = 0;
 int preserve_times = 0;
 int preserve_xattrs = 0;
 mode_t orig_umask = 002;
@@ -90,3 +91,27 @@ struct filter_list_struct daemon_filter_list;
 {
 	return "tester";
 }
+
+#if defined SUPPORT_FILEFLAGS || defined SUPPORT_FORCE_CHANGE
+ uint32 make_mutable(UNUSED(const char *fname), UNUSED(mode_t *mode), UNUSED(uint32 fileflags), UNUSED(uint32 iflags))
+{
+	return 0;
+}
+
+ int undo_make_mutable(UNUSED(const char *fname), UNUSED(uint32 fileflags))
+{
+	return 0;
+}
+
+ int make_parentdir_mutable(UNUSED(const char *fname), UNUSED(uint32 iflags), UNUSED(char *parent_dirbuf), UNUSED(int parent_dirbuf_size))
+{
+	return 0;
+}
+#endif
+
+#ifdef SUPPORT_XATTRS
+ int x_lstat(UNUSED(const char *fname), UNUSED(STRUCT_STAT *fst), UNUSED(STRUCT_STAT *xst))
+{
+	return -1;
+}
+#endif
diff --git a/util.c b/util.c
--- a/util.c
+++ b/util.c
@@ -125,7 +125,7 @@ NORETURN void overflow_exit(const char *str)
 
 /* This returns 0 for success, 1 for a symlink if symlink time-setting
  * is not possible, or -1 for any other error. */
-int set_modtime(const char *fname, time_t modtime, mode_t mode)
+int set_modtime(const char *fname, time_t modtime, mode_t mode, uint32 fileflags)
 {
 	static int switch_step = 0;
 
@@ -138,7 +138,7 @@ int set_modtime(const char *fname, time_t modtime, mode_t mode)
 	switch (switch_step) {
 #ifdef HAVE_UTIMENSAT
 #include "case_N.h"
-		if (do_utimensat(fname, modtime, 0) == 0)
+		if (do_utimensat(fname, modtime, 0, mode, fileflags) == 0)
 			break;
 		if (errno != ENOSYS)
 			return -1;
@@ -148,7 +148,7 @@ int set_modtime(const char *fname, time_t modtime, mode_t mode)
 
 #ifdef HAVE_LUTIMES
 #include "case_N.h"
-		if (do_lutimes(fname, modtime, 0) == 0)
+		if (do_lutimes(fname, modtime, 0, mode, fileflags) == 0)
 			break;
 		if (errno != ENOSYS)
 			return -1;
@@ -167,10 +167,10 @@ int set_modtime(const char *fname, time_t modtime, mode_t mode)
 
 #include "case_N.h"
 #ifdef HAVE_UTIMES
-		if (do_utimes(fname, modtime, 0) == 0)
+		if (do_utimes(fname, modtime, 0, mode, fileflags) == 0)
 			break;
 #else
-		if (do_utime(fname, modtime, 0) == 0)
+		if (do_utime(fname, modtime, 0, mode, fileflags) == 0)
 			break;
 #endif
 
diff --git a/xattrs.c b/xattrs.c
--- a/xattrs.c
+++ b/xattrs.c
@@ -1041,7 +1041,7 @@ int set_stat_xattr(const char *fname, struct file_struct *file, mode_t new_mode)
 	mode = (fst.st_mode & _S_IFMT) | (fmode & ACCESSPERMS)
 	     | (S_ISDIR(fst.st_mode) ? 0700 : 0600);
 	if (fst.st_mode != mode)
-		do_chmod(fname, mode);
+		do_chmod(fname, mode, ST_FLAGS(fst));
 	if (!IS_DEVICE(fst.st_mode))
 		fst.st_rdev = 0; /* just in case */
 
diff -up a/config.h.in b/config.h.in
--- a/config.h.in
+++ b/config.h.in
@@ -70,6 +70,9 @@
 /* Define to 1 if vsprintf has a C99-compatible return value */
 #undef HAVE_C99_VSNPRINTF
 
+/* Define to 1 if you have the `chflags' function. */
+#undef HAVE_CHFLAGS
+
 /* Define to 1 if you have the `chmod' function. */
 #undef HAVE_CHMOD
 
diff -up a/configure.sh b/configure.sh
--- a/configure.sh
+++ b/configure.sh
@@ -7425,6 +7425,7 @@ fi
 
 for ac_func in waitpid wait4 getcwd strdup chown chmod lchmod mknod mkfifo \
     fchmod fstat ftruncate strchr readlink link utime utimes lutimes strftime \
+    chflags \
     memmove lchown vsnprintf snprintf vasprintf asprintf setsid strpbrk \
     strlcat strlcpy strtol mallinfo getgroups setgroups geteuid getegid \
     setlocale setmode open64 lseek64 mkstemp64 mtrace va_copy __va_copy \
diff -up a/proto.h b/proto.h
--- a/proto.h
+++ b/proto.h
@@ -274,6 +274,9 @@ int read_ndx_and_attrs(int f_in, int *if
 void free_sums(struct sum_struct *s);
 mode_t dest_mode(mode_t flist_mode, mode_t stat_mode, int dflt_perms,
 		 int exists);
+uint32 make_mutable(const char *fname, mode_t *mode_ptr, uint32 fileflags, uint32 iflags);
+int undo_make_mutable(const char *fname, uint32 fileflags);
+int make_parentdir_mutable(const char *fname, uint32 iflags, char *parent_dirbuf, int parent_dirbuf_size);
 int set_file_attrs(const char *fname, struct file_struct *file, stat_x *sxp,
 		   const char *fnamecmp, int flags);
 RETSIGTYPE sig_int(UNUSED(int val));
@@ -297,11 +300,12 @@ void set_socket_options(int fd, char *op
 int do_unlink(const char *fname);
 int do_symlink(const char *fname1, const char *fname2);
 int do_link(const char *fname1, const char *fname2);
-int do_lchown(const char *path, uid_t owner, gid_t group);
+int do_lchown(const char *path, uid_t owner, gid_t group, mode_t mode, uint32 fileflags);
 int do_mknod(const char *pathname, mode_t mode, dev_t dev);
 int do_rmdir(const char *pathname);
 int do_open(const char *pathname, int flags, mode_t mode);
-int do_chmod(const char *path, mode_t mode);
+int do_chmod(const char *path, mode_t mode, uint32 fileflags);
+int do_chflags(const char *path, uint32 fileflags);
 int do_rename(const char *fname1, const char *fname2);
 int do_ftruncate(int fd, OFF_T size);
 void trim_trailing_slashes(char *name);
@@ -311,10 +315,10 @@ int do_stat(const char *fname, STRUCT_ST
 int do_lstat(const char *fname, STRUCT_STAT *st);
 int do_fstat(int fd, STRUCT_STAT *st);
 OFF_T do_lseek(int fd, OFF_T offset, int whence);
-int do_utimensat(const char *fname, time_t modtime, uint32 mod_nsec);
-int do_lutimes(const char *fname, time_t modtime, uint32 mod_nsec);
-int do_utimes(const char *fname, time_t modtime, uint32 mod_nsec);
-int do_utime(const char *fname, time_t modtime, UNUSED(uint32 mod_nsec));
+int do_utimensat(const char *fname, time_t modtime, uint32 mod_nsec, mode_t mode, uint32 fileflags);
+int do_lutimes(const char *fname, time_t modtime, uint32 mod_nsec, mode_t mode, uint32 fileflags);
+int do_utimes(const char *fname, time_t modtime, uint32 mod_nsec, mode_t mode, uint32 fileflags);
+int do_utime(const char *fname, time_t modtime, UNUSED(uint32 mod_nsec), mode_t mode, uint32 fileflags);
 void set_compression(const char *fname);
 void send_token(int f, int32 token, struct map_struct *buf, OFF_T offset,
 		int32 n, int32 toklen);
@@ -334,7 +338,7 @@ int fd_pair(int fd[2]);
 void print_child_argv(const char *prefix, char **cmd);
 NORETURN void out_of_memory(const char *str);
 NORETURN void overflow_exit(const char *str);
-int set_modtime(const char *fname, time_t modtime, mode_t mode);
+int set_modtime(const char *fname, time_t modtime, mode_t mode, uint32 fileflags);
 int mkdir_defmode(char *fname);
 int create_directory_path(char *fname);
 int full_write(int desc, const char *ptr, size_t len);
diff -up a/rsync.1 b/rsync.1
--- a/rsync.1
+++ b/rsync.1
@@ -417,6 +417,7 @@ to the detailed description below for a
  \-K, \-\-keep\-dirlinks         treat symlinked dir on receiver as dir
  \-H, \-\-hard\-links            preserve hard links
  \-p, \-\-perms                 preserve permissions
+     \-\-fileflags             preserve file\-flags (aka chflags)
  \-E, \-\-executability         preserve executability
      \-\-chmod=CHMOD           affect file and/or directory permissions
  \-A, \-\-acls                  preserve ACLs (implies \-p)
@@ -448,7 +449,10 @@ to the detailed description below for a
      \-\-delete\-after          receiver deletes after transfer, not before
      \-\-delete\-excluded       also delete excluded files from dest dirs
      \-\-ignore\-errors         delete even if there are I/O errors
-     \-\-force                 force deletion of dirs even if not empty
+     \-\-force\-delete          force deletion of dirs even if not empty
+     \-\-force\-change          affect user/system immutable files/dirs
+     \-\-force\-uchange         affect user\-immutable files/dirs
+     \-\-force\-schange         affect system\-immutable files/dirs
      \-\-max\-delete=NUM        don'\&t delete more than NUM files
      \-\-max\-size=SIZE         don'\&t transfer any file larger than SIZE
      \-\-min\-size=SIZE         don'\&t transfer any file smaller than SIZE
@@ -638,7 +642,8 @@ specified, in which case \fB\-r\fP is no
 .IP 
 Note that \fB\-a\fP \fBdoes not preserve hardlinks\fP, because
 finding multiply\-linked files is expensive.  You must separately
-specify \fB\-H\fP.
+specify \fB\-H\fP.  Note also that for backward compatibility, \fB\-a\fP
+currently does \fBnot\fP imply the \fB\-\-fileflags\fP option.
 .IP 
 .IP "\-\-no\-OPTION"
 You may turn off one or more implied options by prefixing
@@ -955,7 +960,7 @@ they would be using \fB\-\-copy\-links\f
 Without this option, if the sending side has replaced a directory with a
 symlink to a directory, the receiving side will delete anything that is in
 the way of the new symlink, including a directory hierarchy (as long as
-\fB\-\-force\fP or \fB\-\-delete\fP is in effect).
+\fB\-\-force\-delete\fP or \fB\-\-delete\fP is in effect).
 .IP 
 See also \fB\-\-keep\-dirlinks\fP for an analogous option for the receiving
 side.
@@ -1142,6 +1147,33 @@ Note that this option does not copy rsyn
 used by \fB\-\-fake\-super\fP) unless you repeat the option (e.g. \-XX).  This
 \(dq\&copy all xattrs\(dq\& mode cannot be used with \fB\-\-fake\-super\fP.
 .IP 
+.IP "\fB\-\-fileflags\fP"
+This option causes rsync to update the file\-flags to be
+the same as the source files and directories (if your OS supports the
+\fBchflags\fP(2) system call).   Some flags can only be altered by the super\-user
+and some might only be unset below a certain secure\-level (usually single\-user
+mode). It will not make files alterable that are set to immutable on the
+receiver.  To do that, see \fB\-\-force\-change\fP, \fB\-\-force\-uchange\fP, and
+\fB\-\-force\-schange\fP.
+.IP 
+.IP "\fB\-\-force\-change\fP"
+This option causes rsync to disable both user\-immutable
+and system\-immutable flags on files and directories that are being updated or
+deleted on the receiving side.  This option overrides \fB\-\-force\-uchange\fP and
+\fB\-\-force\-schange\fP.
+.IP 
+.IP "\fB\-\-force\-uchange\fP"
+This option causes rsync to disable user\-immutable
+flags on files and directories that are being updated or deleted on the
+receiving side.  It does not try to affect system flags.  This option overrides
+\fB\-\-force\-change\fP and \fB\-\-force\-schange\fP.
+.IP 
+.IP "\fB\-\-force\-schange\fP"
+This option causes rsync to disable system\-immutable
+flags on files and directories that are being updated or deleted on the
+receiving side.  It does not try to affect user flags.  This option overrides
+\fB\-\-force\-change\fP and \fB\-\-force\-schange\fP.
+.IP 
 .IP "\fB\-\-chmod\fP"
 This option tells rsync to apply one or more
 comma\-separated \(dq\&chmod\(dq\& strings to the permission of the files in the
@@ -1442,13 +1474,14 @@ See \fB\-\-delete\fP (which is implied)
 Tells \fB\-\-delete\fP to go ahead and delete files
 even when there are I/O errors.
 .IP 
-.IP "\fB\-\-force\fP"
+.IP "\fB\-\-force\-delete\fP"
 This option tells rsync to delete a non\-empty directory
 when it is to be replaced by a non\-directory.  This is only relevant if
 deletions are not active (see \fB\-\-delete\fP for details).
 .IP 
-Note for older rsync versions: \fB\-\-force\fP used to still be required when
-using \fB\-\-delete\-after\fP, and it used to be non\-functional unless the
+This option can be abbreviated \fB\-\-force\fP for backward compatibility.
+Note that some older rsync versions used to still require \fB\-\-force\fP
+when using \fB\-\-delete\-after\fP, and it used to be non\-functional unless the
 \fB\-\-recursive\fP option was also enabled.
 .IP 
 .IP "\fB\-\-max\-delete=NUM\fP"
@@ -2004,7 +2037,7 @@ with older versions of rsync, but that a
 verbose messages).
 .IP 
 The \(dq\&%i\(dq\& escape has a cryptic output that is 11 letters long.  The general
-format is like the string \fBYXcstpoguax\fP, where \fBY\fP is replaced by the
+format is like the string \fBYXcstpogfax\fP, where \fBY\fP is replaced by the
 type of update being done, \fBX\fP is replaced by the file\-type, and the
 other letters represent attributes that may be output if they are being
 modified.
@@ -2074,7 +2107,7 @@ sender\(cq\&s value (requires \fB\-\-own
 A \fBg\fP means the group is different and is being updated to the
 sender\(cq\&s value (requires \fB\-\-group\fP and the authority to set the group).
 .IP o 
-The \fBu\fP slot is reserved for future use.
+The \fBf\fP means that the fileflags information changed.
 .IP o 
 The \fBa\fP means that the ACL information changed.
 .IP o 
